Electrical conduit containing hydrorefined oil

ABSTRACT

An oil impregnated electrical conduit comprises a conductive metal, a cellulosic insulator, and a hydrorefined insulation oil, wherein the hydrorefined oil has a viscosity in the range of 10012,000 SUS at 100* F., contains 10-65 weight percent aromatics (by gel analysis) and less than 10 p.p.m. of basic nitrogen (preferably less than 5 p.p.m. and typically less than 2 p.p.m.). Typically, such an oil can contain more than 10 p.p.m. of total nitrogen (e.g., 15-600 p.p.m.) depending on the viscosity of the oil. Preferably, the hydrorefined oil is naphthenic or aromatic (by VGC classification). A preferred conduit is an oil-filled electrical cable wherein the cellulosic insulator is paper and is wrapped around the conductive metal. A preferred paper is capacitor grade Kraft paper of relatively high density and can be creped or microcreped. The cellulosic insulator can also comprise chemically treated cellulose such as cyanoethylated cellulose or acetylated cellulose.

O United States Patent 1 1 3,586,752

[72) Inventors Ivor W. Mills 701,131 1/1965 Canada 174/25 Media;

I 2 l l A I No 2 32;? waumgiord Attorneys-George L. Church, Donald R.Johnson, Wilmer E.

PP v

[ Filed g 18. I969 McCorquodale,.Ir. and Barry A. Bisson Patented June22,1971

[73] Assignce Sun ()il Compan). Philadelphia. Pa.

[54] ELECTRICAL CONDUIT CONTAINING ABSTRACT: An oil impregnatedelectrical conduit comprises HYDROREFINED OIL a conductive metal, acellulosic insulator, and a hydrorefined l2 Claims,3 Drawing Figs.insulation oil, wherein the hydrorefined oil has a viscosity in therange of l00l2,000 SUS at 100 F., contains 10-65 52 U.S. Cl 1514/2154weight percent aromatics (by gel analysis) and less than I 0 l 51 I in!CI 01b 9/06 p.p.m. of basic nitrogen (preferably less than 5 p.p.m. andtypi 174/25 25 ically less than 2 ppm). Typically, such an oil cancontain more than 10 p of total nitrogen (egn pp I 208/14 252/50depending on the viscosit of the oil. Preferably, the

5 Refemnm Cited hydrorefined oil is naphthenie or aromatic (byVGCclassifica- UNITED STATES PATENTS tion). A preferred conduit 18 anoil-filled electrical cable wherein the cellulosic insulator is paperand is wrapped 116L705 12/1964 174/25 around the conductive metal. Apreferred paper is capacitor l 1 10/1968 wYnkoop at 208/ grade Kraftpaper of relatively high density and can be creped l7s7olo 7/1929174/120 or microcreped. The cellulosic insulator can also compriseFOREIGN PATENTS chemically treated cellulose such as cyanoethylatedcellulose 896,065 5/1962 Great Britain 174/25 or acetylated cellulose-PATENIEIIJ III22IQII 3586752 SHEET 1 OF 3 FIGuRE I TOTAL NITROGEN ANDBASIC NITROGEN vs ULTRAVIOLET ABSORPTIVITY FOR NAPTHENIC OILS OFDIFFERING V.|SCO S|TY(AT IOO F) Goo- I6O00 sus- TOTAL NITROGEN AFTERHYDROREFINING 500-.

. I I 2500 sus BASIC NITROGEN AFTER HYDROREFINING E 300 3 2500 sus A z Ig oeooosus- 200- I z SUS X o zsoosus.

22255 I I 500 SUS HYDRGREFINING Ioof A Ioosus 0500 s us I50 sus x I vI50 sus 5o sus I I I o I 2 5-4 5 G 7 a 9 I0 II ULTRAVIOLET AasoRPTI'vITYAT 260 1.

INV NTQR ATTORNEY PATENIH] JUN22 lsm SHEET 2 BF 3 FIGURE 2 7 BASICNITROGEN CONTENT VS ACID ACTIVATED CLAY DOSAGE 04 I0 v ACIDCLAY'(EQUIVALENT TO 10.2 mg KOH per gram) LEI/BBL.

ATTORNEY PAI'ENTEDJUNZZ m SHEET 3 0F 3 FIGURE 3 INVENTORS .IVOR w. MILLSI GLENN R. DIMELER JOHN J. MELCHIORE B ATTORNEY ELECTRICAL CONDUITCONTAINING IIYDROREFINED OIL CROSS REFERENCES TO RELATED APPLICATIONSThe present application is copending with the following listedapplications, all of which are assigned to the Sun Oil Company, to whomthe present application is also assigned:

Serial Filint. No. date Title 622,398 1 3-13-67 "Clay Treatment oflIydrorelined ils"---Ivor W.

Mills, Glenn R. l)imeler. 652,0'ltL... 7-10-67 "Process for lrodneinp.Cable 0115 by Sequential Refining Steps"--lvor W. Mills, Glenn 1t.

l)i|neler. (136,493... -5(i7 Process for Preparing an Aromatic ()ii andNote Discoloring Rubber Composition (.ontnining Said ()il"- -Ivor Mills,(llenn R. Dimeler, Merritt Kirk, Jr. 73U,l|lm 5-22-68 llydrorelined'1rmrs1ormer ()i1 and Process ul .\lanulaetur Ivor W. Mills, (llenn It.I)lI1l('Il'I. 812,516. 2-1lHiil Catulytiellydmllnishingoi PetroleumDistillates in the Lubricating ()il Boiling Range" -lvor W. Mills,(llenn It. l)imeler, Merritt Kirk, Jr., Albert '1. ()lenzak. 860,717....Hydrorelincd Lube Oil and Process of Manulaeture-lvor Mills, Glenn R.Dimeler. 850,778.... "Process for Preparing lligll Viseosity IIV(Il'0l'i-- lined Callie ()il Ivor .\lills, (llenn It. 'Diineler,William A. Atkinson, Jr., James I.

Hoffman. Blended Hydrocarbon Oil and Process of Mann- 850,Tlti.

. l'nttlue -lv or Mills. (llenn It. l)inieler.

1 Patent No. 3.460.358, issued August Infill. 1 Patent No. 3,502,567,issued Mnreh .24, 111711. 3 Filed of even date with present npplieation.

The disclosures of all the above-referred to applications are herebyincorporated herein by reference, particularly as to disclosure thereindirected to hydrorefined oils in the lube viscosity range, to uses ofsuch oils, and to the production of such oils.

All of the above referred to copending applications contain disclosurerelating to conditions which can be used to produce severelyhydrorefined petroleum distillate in the lubricating oil viscosityrange.

BACKGROUND OF TH E INVENTION In copending application Ser. No. 622,398,filed Mar. 13, 1967 and titled Clay Treatment of Hydrorefined CableOils," a process is claimed forproducing animproved cable oil having anASTM D-l934 aged dissipation factor (ADF) below 0.010 in the absence ofadded oxidation inhibitors, from a hydrogenated naphthenic oil having aviscosity in the range of 500-2000 SUS at 100 F., an ultravioletabsorbency (UVA) less then 8 at 260 millimicrons and having an ADFgreater than 0.015, comprising contacting said oil at a temperature inthe range of 100400 F. with an adsorbent comprising .an acid-activatedadsorbent clay in an amount per barrel of oil such that from 10--90grams of KOH would be required to neutralize the acidity of theacid-activated adsorbent clay. Also claimed is a naphthenic electricaloil having a viscosity in the range of 5002000 SUS at 100 F., having anADF less than 0.010 in the absence of added oxidation inhibitors, andwhich requires at least 75 hours at PFVO test conditions to reach a 6percent power factor. It was further disclosed that, in the case of thehigh viscosity cable oils (4000--6000 SUS at 100 F.), a relativelyinexpensive fullers earth bleaching clay was preferred as the adsorbentfor such a hydrorefined oil and that the dosage of clay was notparticularly critical insofar as the ADF of the resulting cable oil wasconcerned.

Also disclosed were hydrogenation conditions and catalysts which couldbe used to severely hydrorefine distillate oils in the lubricating oilviscosity range (35 and higher SUS at 100 F.). It was further disclosedthat such severe hydrogenation should be conducted so that the 260 UVAof the feed to the hydrogenation step be reduced at least 40 percent.

Further disclosed in said application, by example, was that the degreeof nitrogen removal caused by the severe hydrorefining can varyaccording to the viscosity of the charge oil (an oil having a viscosityof 107 SUS and containing 170 p.p.m. N produced an oil containing 47p.p.m. N; whereas, an

oil having a viscosity of 2901 SUS and containing 467 p.p.m. of Nproduced, under the same hydrogenation conditions, an oil containing 313p.p.m. ofN).

BRIEF SUMMARY OF TI-IEINVENTION It has been discovered that, inhydrorefined lubes having viscosities of 100 SUS or higher at 100 F.(whether paraffins, naphthenic or aromatic), the total nitrogen contentis not a reliable indicator of the stability of the oil under allconditions of use (as with refrigeration oils, textile oils, electricaloils, transmission fluids, etc.), but that the basic" nitrogen contentof the hydrogenated oil is an important indicator of how the oil (orblends containing the oil) will respond under severe conditions of use.

Although the hydrorefined cable oils disclosed in the abovereferred toapplications, Ser. Nos. 622,398 and 652,026, are satisfactory as aninsulating medium in most types of electrical conduit, it has beenfoundthat, in oil-impregnated electrical conduits (such as cables) whichcontain a cellulosic insulator, the basic nitrogen content of thehydrorefined oil must be less than 10 p.p.m. (preferably less than 5p.p.m.) in order that the resulting conduit can have a long life underservice conditions. The basic nitrogen content of the hydrorefinedinsulating oil is especially critical when the cellulosic insulatorcomprises a Kraft paper or board or a chemically modified Kraft paper orboard.

A novel hydrorefined oil if improved stability under severe conditionsof use has a viscosity in the range of 100- 12,000 SUS at 100 F.,contains l0--44 percent gel aromatics and less than 10 p.p.m.(preferably less than 5 p.p.m., more preferably less than .2 p.p.m.) ofbasic nitrogen. Typically, such an oil can contain more than 10 p.p.m.of total nitrogen (e.g., l5--600 p.p.m.) depending on the viscosity ofthe oil. Preferably, the hydrorefined oil is naphthenic or aromatic (byVGC classification). The basic nitrogen in such severely hydrorefinedlube oils (typically 15-400 p.p.m.) can be reduced to less than 10p.p.m. by a process comprising contacting the hydrorefined oil with anacidic adsorbent (such as an adsorbent comprising an acid-activatedclay), preferably at 50 1 50 F., or by contacting the hydrorefined oilwith sufficient quantities of a mineral acid (e.g., 120 percent H SOfollowed by a basic wash to neutralize the oil and remove impurities (asby the procedures referred to in the commonly assigned copendingapplication Ser. No. 657,438 of Schneider and Stuart entitled RubberContaining Acid- Treated Oils And Its Preparation, the disclosure ofwhich is hereby incorporated herein). More preferably, the contacting isat a temperature in the range of 50--l00 F. (e.g., 70 F.). The oil whichhas been acid contacted and neutralized can be further finished (as maybe desired for an electrical oil) by adsorbent contacting, as with afullers earth bleaching clay (attapulgite), activated carbon, alumina,or a crystalline alumino-silicate zeolite (e.g., Linde 5A, or 13Xmolecular sieves), an acid-activated clay or combinations of two or moresuch adsorbents (e.g., see US. Pat. No. 3,369,993). A preferredadsorbent combination is an admixture of attapulgite and acid-activatedclay.

BRIEF DESCRIPTION OF .THE DRAWINGS In the drawings, FIG. I is a plot ofthe 260 UVA versus the nitrogen content (total or basic) of hydrorefinednaphthenic oils of various viscosities. The hydrorefining of each chargeoil was at 650 F., 0.5 LHSV (of the fresh feed), 1200 p.s.i.g. of 75percent hydrogen (at the reactor inlet) with sulfided NiMo oxides onalumina as the catalyst. Also plotted is the basic nitrogen content ofthe charge stock (in the 2500 SUS viscosity range) before hydrorcfining.

FIG. 2 is a plot of the pounds of acid-activated clay (equivalent to10.2 mg. KOH per gram) required per barrel of hydrorefined oil to reducethe basic nitrogen to a given p.p.m. level in two of the severelyhydrorefined naphthenic distillates from which the data plotted 111 FIG.1 was obtained The basic nitrogen is on a logarithmic scale, indicatingthat at lower concentrations it becomes increasingly more difficult toremove basic nitrogen with a single contacting step.

FIG. 3 shows a cable, in fragmentary perspective view, having a centralstranded conductor 1 surrounded throughout its entire length by asemiconducting layer 2 of carbon black paper. Both the conductor 1 andthe semiconducting layer 2 surrounding it are covered by a substantiallycontinuous concentric insulating layer 3 which is composed of manylayers of helically wrapped paper tape saturated with a hydrorefined oilhaving a viscosity in the range of l12,000 SUS at 100 F. and containing10-65 weight percent aromatics and less than 10 p.p.m. of basicnitrogen. The insulating layer 3 is shielded in turn, by an outersemiconducting layer 4 of carbon black paper and a protective leadsheath 5.

FURTHER DESCRIPTION OF THE INVENTION Petroleum fractions (e.g.,distillates, extracts, raffinates, reformer bottoms, cycle oilfractions, etc.) in the lubricating oil viscosity range (SS-14,000 SUSat 100 F.) can be severely hydrorefined (e.g., at 600 F., 1200 p.s.i.g.of 80 percent hydrogen, 0.3 LHSV, presulfided Ni-Mo oxide catalyst) toproduce a hydrogenated oil having a lighter ASTM color, a lower (by aleast 40 percent) ultraviolet absorpitivity at 260 millimicrons andcontaining appreciably less total nitrogen (and, if desired, lower gelaromatics) than was in the charge to the hydrorcfining stage.

With some charges, such as parafi'tnic distillates, dewaxing and/ordeasphalting can be advantageous prior to hydrorefining. Preferably, toinsure longer catalyst life and to reduce hydrogen consumption, when thepetroleum fraction is derived from a stock containing naphthenic acids,such acids should be removed (or substantially reduced) prior tohydrorefining as by the processes disclosed in the following U.S. Pat.Nos. 1,603,174; 2,770,580; 2,795,532; 2,966,456; and 3,080,312.

In case of light lubes (e.g.,having a viscosity in the range of 35-65SUS at 100 R), such as the transformer oils, the total nitrogenremaining in the oil after a single stage of severe hydrogenation canfrequently be less than 10 p.p.m. (typically, less than 5 p.p.m.l-Iydrorefining can also be conducted (in a single stage or in multiplestages) so as to obtain a hydrorefined (or hydroaromatized) oil withsuch low nitrogen and an increased gel aromatic content (as disclosed inthe aforementioned application, Ser. No. 636, 636,493).

therefore, in light lubes and, particularly, in transformer oils severehydrogenenation in a single stage is normally sufficient to reduce thebasic nitrogen to less than 5 p.p.m. Generally, basic nitrogen is not aproblem in such severely hydrorefined light lubes. Similarly, when thecharge to a severe hydrorefining stage consists essentially of aparaffinic distillate in the lubricating oil boiling range, severehydrogenation in a single stage is usually sufficient to effectivelyreduce both total and basic nitrogen to less than p.p.m.

However, as is illustrated in FIG. 1 in the drawings attached hereto,when the charge stock is naphthenic or aromatic distillate (including araftinate or extract product from solvent extraction of a naphthenicdistillate), having a viscosity greater than about 100 SUS, severehydrogenation in a single stage, as to an ultraviolet absorptivity at260 millimicrons (i.e., 260 UVA) in the range of 3 for a 150 SUS oil,cannot economically be used to reduce the basic nitrogen content belowabout 10 p.p.m., nor the total nitrogen content below about 20 p.p.m. Ascan be seen from FIG. 1, both the total and the basic nitrogen contentsof such hydrorefined oils typically are greater as the viscosity of theoil increases. This is probably due to less efficient utilization of thehydrogen caused by the hindering effect of the larger oil molecules onhydrogen diffusion.

Also shown, in FIG. 2 is the dramatic degree to which such basicnitrogen can be removed from such a hydrorefined oil by means of anacidic adsorbent, particularly, acid-activated adsorbent clay.

For many uses (as in dark colored rubber vulcanizates or in electricalcables where the oil is not in contact with Kraft paper) such severelyhydrorefined oils exhibit satisfactory performance even at totalnitrogen levels in the range of 30-900 p.p.m. (about 50 percent of thetotal nitrogen being basic" nitrogen). For certain end uses (such as intextile spinning oils, light colored oil-rubber vulcanizate, cableswhere the oil is in contact with Kraft paper, and in refigerator oilssubjected to high operating temperatures) a much more satisfactoryperformance is obtained with a novel hydrorefined oil which has aviscosity in the range of -l2,000 SUS at 100 F contains 5-50 percent(typically 10-44 percent) of gel aromatics, and contains less than 10p.p.m. of basic nitrogen (preferably, less than 5 p.p.m. and morepreferred less than2 p.p .m v

v The phrase total nitrogen" refers to the nitrogen content of an oil asdetermined by such methods as that of P. Gouverneur, Anal. Chim. Acta,26 1962) 212 or, more preferred, the modified Gouvemeur method describedby Smith, A. .I. et al. in Anal. Chim. Acta, 40 1968) 341-343.

The phrase basic nitrogen" refers to those nitrogen compounds present incrudes, petroleum distillates and residues which have a basic ionizationconstant, K greater than 10. A preferred analytic method determining thecontent of such basic nitrogen compounds in hydrorefined oils in thelube oil viscosity range, involves dissolving a sample of the oil in anappropriate solvent and potentiometrically titrating the solution withperchloric acid and acetic acid. In the case of lightcolored oils, thesolvent can be glacial acetic acid and paranaphthol-benzein can be usedas a colorometric indicator as an alternative to the potentiometricprocedure. Dark samples and heavier oils are dissolved inchlorobenzene-acetic acid solvent and titrated potentiometrically(utilizing a pH meter or its equivalent and a glass-calomel electrodesystem).

For the potentiometric titration, the procedure is to place a 20-gramsample of the oil in a 250 ml. tall-form titration beaker and add about100 milliliters of a mixture of equal quantities of glacial acetic acidand chlorobenzene. The sample is thentitrated potentiometrically, atroom temperature, while being stirred continually by a magnetic stirrer,with 0.01 N perchloric acid in glacial acetic acid to which has beenadded about 20 ml. of acetic anhydride for each liter of glacial aceticacid' (in order to insure the removal of any water that might bepresent).'The weight percent basic nitrogen is calculated as follows:

PPM Basie N W Where:

V ml. titrant for sample V m1. titrant for blank N normality ofperchloric acid W= sample weight (grams) This potentiometric titrationcan be used to determine the basic nitrogen content of a hydrorefinedoil in the range of 1 to at least 2000 p.p.m. and, in the range of 1-10p.p.m. is at least accurate to within 1 p.p.m. when corrections are madefor interferences by hydroxides, some oxides, carbonates, naphthenates,and similar bases (if these are present in the sample).

The phrases severe hydrorefining or hydrogenation refer to processesconducted in the presence of a hydrogenation catalyst at from about500775 F with hydrogen of 50- -100 percent purity, and from 800-3000p.s.i. of hydrogen at the reactor inlet (at total pressures from800-6000 p.s.i.g.) at a fresh feed liquid hourly space velocity (Ll-ISV)of from 0.1-8.0 (usually below 2.0), preferably conducted either invapor phase or trickle phase. Such hydrogenation or severe hydrorefiningis to be distinguished from hydrocracking in that the productionofoverhead" (i.e hydrocarbons boiling below 485 F.) is less than 25percent by volume per pass through the reactor (and, typically, lessthan percent). Product recycle, for example, as in US. Pat. No.2,900,433 can be used to increase severity. Recycle liquid hourly spacevelocity can vary from 0 to 20', however, we prefer to operate at totalliquid throughputs that obtain at greater than 25 percent of floodingvelocity and more preferably at from 40-98 percent of flooding velocity.

Preferably, the temperature is below that at which substantial crackingoccurs, that is, no more than 20 weight percent (preferably less than 10percent) of the feed stock is converted to material boiling below 300 F.in a single pass through the reactor. Although the maximum hydrogenationtemperature which will not produce substantial cracking is somewhatdependent upon the space velocity, the type of catalyst and thepressure, generally it is below 750 F. but can be as high as 785 F. Toallow a margin or safety, we prefer to operate below 7t)0 F. (exceptwhen it is desired to obtain a hydrogenateil oil containing more gelaromatics than are in the charge). At total pressures below about 2000p.s.i. we prefer a temperature below about 660 F., since above thattemperature the degradation of oil viscosity can become larger.

Typical of such severe hydrorefining methods, when conducted within theaforementioned processing conditions, are those of U.S. Pat. Nos.2,968,614; 2,993,855; 3,102,963; 3,114,710; 3,144,404; and 3,278,420;and those of the previously referred to copending applications, Ser.Nos. 622,398; 652,026; 636,493; 730;999 and 812,516. The terms severelyI hydrorefined oil" or hydrogenated oil" include the products,

within the lubricating oil boiling range, of such severe hydrorefiningor hydrogenaton. "One characteristic of a severely hydrorefined orhydrogenated oil is that the ratio of monocyclic aromatics to polycyclicaromatics is significantly greater than in hydrotreated oils orconventional distillate oils.

Where the desired hydrorefined oil is to be of the naphthenic class, apreferred charge to the hydrogenation reactor can be obtained by vacuumdistillation of naphthenic crude oils (as in US. Pat. No. 3,184,396),especially those napthenic crude oils wherein the 1500-3000 SUS (at 100F.) distillate fractions have viscosity-gravity constants from 0.84 to0.92. Preferably, such a charge stock should be substantially free ofnaphthenic acids prior to the hydrorefining.

Usually materials boiling below about 600 F. (including residual H S, NHetc.) are removed from the hydrorefined oils, as by atmosphericdistillation (and the viscosity can also be adjusted by choice ofdistillation end point) prior to clay contacting (if the oils are to beclay finished);

The viscosity of the base oil, or of the final hydrorefined oil, can beadjusted by the addition of other oils of higher or lower viscosity andwhich are within the lube oil boiling range. For example, a preferredcable oil having a viscosity of 100 F. in the range of 500-2000 SUS canbe obtained by blending hydrogenated oil having a viscosity from 300600SUS with hydrogenated oil having a viscosity from 1500-3000 SUS and thencontacting the resulting blend of hydrogenated oils with sufficientacidic adsorbent or mineral acid to reduce the basic nitrogen content ofthe oil to below 10 p.p.m.

FURTHER DESCRIPTION OF THE DRAWINGS FIG. 1 herein illustrates thetypical contents of total nitrogen and basic nitrogen for severelyhydrorefined naphthenic oils in the viscosity range from 50 to over 6000SUS. The curves can be extended (either by mathematical means or .by useof a French curve), to obtain typical nitrogen contents of oils as highas 12,000 SUS at 100 F.

In FIG. 1, two curves have been drawn to illustrate the relationshipbetween the total and basic nitrogen content of severely hydrorefinedoils of a number of viscosity ranges. The

nitrogen content has been plotted against the 260 UVA, since the 260 UVAindicates the degree to which the oils have been hydrogenated. Alsoillustrated in a third curve is the basic nitrogen content ofthe chargeoils before hydrorefining.

For example, in FIG. 2, a 2500 SUS naphthenic distillate (which wassubstantially free from naphthenic acid) was hydrorefined at 650 F., 0.5LHSV at 1200 p.s.i.g. of percent hydrogen (at the reactor. inlet). The2500 SUS oil contained about 270 p.p.m. of basic nitrogen before thehydrorefining. The hydrorefined oil contained about p.p.m. of nitrogen(and about 350 p.p.m. total nitrogen). The UVA of the 2500 SUSdistillate before hydrorefining was about 10,8 and, the hydrorefined oilhad a 260 UVA of about 5.6, indicating a severe hydrogenation for such arelatively proached, it becomes progressively more difficult to removebasic nitrogen with the acid clay adsorbent. The two curves in FIG. 2illustrate that as the viscosity of the hydrorefined oil increases,greater amounts of acid clay are necessary to reduce the basic nitrogencontent to less than 10 p.p.m. (and or more preferably to less than 5p.p.m.). With the more highly viscous, hydrorefined oils, it becomesmore economical to utilize a mineral acid, and to dilute the oil with anonreactive, less viscous, lower boiling solvent (such as iso-octane orgas oil). Such contacting with a mineral acid can be by the processesshown in the previously referred to copending applications, Ser. No.622,398 and Ser. No. 652, 026. Other preferred processes for removingbasic nitrogen from such oils can be found in the copending applicationof Scheider and Stuart, Ser. No. 657,438.

ILLUSTRATIVE EXAMPLES Example I A 2500 SUS naphthenic distillate (whichwas substantially free from naphthenic acid) was hydrorefined at 650 F.,0.5 LHSV at 1200 p.s.i.g. of 80 percent hydrogen (at the reactor inlet).The 2500 SUS oil contained about 270 p.p.m. of basic nitrogen before thehydrorefining. The hydrorefined oil contained about 180 p.p.m. ofnitrogen and about 350 p.p.m. total nitrogen. The UVA of the 2500 SUSdistillate before hydrorefining was about 10.8 and, the hydrorefined oilhas a 260 UVA of about 5.6, indicating a severe hydrogenation for such arelatively highly viscous distillate. The appropriate values for thecharge and hydrogenated oil produced from this charge are plotted inFIG. 1.

Example 11 FIG. 2 of the drawings illustrates the degree to which thebasic nitrogen is a hydrorefined oil can be reduced by contacting theoil with various amounts of an acid-activated clay. The upper curve inFIG. 2 shows the nitrogen levels which were obtained by such contact ofthe 2500 SUS hydrorefined oil of Example I. In the figure, the acid clayused had an acidity equivalent to 10.2 mg. KOH per gram. In FIG. 2, thebasic nitrogen is plotted on a logarithmic scale, indicating that as thelower levels of nitrogen content are approached, it

' becomes progressively more difficult to remove basic nitrogen with theacid clay adsorbent. The two curves in FIG. 2 illustrate that as theviscosity of the hydrorefined oil increases, greater amounts of acidclay are necessary to reduce the basic nitrogen content to less than 10p.p.m. (and or more preferably to less than 5 p.p.m.). With the morehighly viscous, hydrorefined oils it becomes more economical to utilizea mineral acid, and to dilute the oil with a nonreactive, less viscous,lower boiling solvent (such as iso-octane or gas oil).

Such contacting with a mineral acid can be by the processes shown in thepreviously referred to copending applications, Ser. No. 622,398 or Ser.No. 652,026. Other preferred processes for removing basic nitrogen fromsuch oils are those shown in the copending application of Schneider andStuart, Ser. No. 657,438. Cables containing Kraft paper and the oilscontaining less than 5 p.p.m. of basic nitrogen show good performanceunder service conditions.

Example 111 A residuum was obtained from the distillation of anaphthenic crude (VGC of 0.89) by the caustic distillation processdescribed in US. Pat. No. 3,184,396. This residuum was distilled under alower pressure than that used in the first distillation and a 35 volumepercent overhead fraction (viscosity 13,000 SUS at 100 F. and 200 SUS at210 F.) was recovered. This overhead will be referred to hereinafter asheavy distillate from heavy residuum" or by the abbreviation HDFHR. TheHDFHR was hydrorefined, in the presence of a sulfided Ni-Mo oxidecatalyst, at a temperature of about 605 F., 1140 p.s.i.g. total pressure(about 75 percent H at reactor inlet), at a 7 to 1 volume ratio ofrecycle to charge and with a reactor gas bleed of 18,000 scfh. Thehydrogenated product (95 volume percent yield) had a viscosity at 100 F.of 8850 SUS and 170 SUS at 210 F. This hydrogenated oil had an initialASTM color of 2.0 and remained stable in color if stored at atemperature below x30 F. when contacted with 10 lb./bbl. of H 50 washedand neutralized and finished with 10 lb./bbl. of attapulgite. The finaloil had an initial power factor (100 C.) of 0.0006 and an aged (with Cu)100 C. power factor of 0.012.

Table I herein reports the additional improvement in electricalproperties which can be obtained when the HDFl-lR" is treated with anacid such as H 80 washed and neutralized prior to the hydrogenationstep. Also shown is the additional improvement which can be obtained bya final contacting with acid-activating clay.

Example IV TABLE l.-8. SUS (AT 100 F.) ABLE (111$ MADE FROM HEAVYDISTILLATE FROM HEAVY RESIDUUM (lll)-i ll it) ASIM dissipation factorBasic nitrogen, p.p.m.

Aged, 1 days (.n,

Step further treatmentol IIDFIIR lntiul at 100 C.

1 Maximum.

I ()ii A 011 1) ()il l) Viscosity, SUS/210 F. (ASTM D2101) 100 130 125Dissipation Factor at 100 C Initial (AS'IM D024) 0.0002 0.0002 0. 00010. 0001 Aged, With Cu, 4 days, (ASTM D024), C. (1)103413) 0. 0121 0.01380. 0183 00006 Total nitrogen, p.p.m o 42!) 430 26R 16 Basic nitrogen.p.p.m 251 250 '15 3 Power factor at (3., 50 to 100 volts per mil. o1krnlt paper impregmtted with oil, percent 7 7 0. 7 0. 3

11:80., plus15/bhl. attapulgitc.

The invention we claim is:

1. In an oil-impregnated electrical cable comprising a conductive metal,a cellulosic insulator, and a hydrorefined electrical insulation oil,the improvement wherein said hydrorefined oil has a viscosity in therange of 100-12,000 SUS at 100 F. and contains l065 weight percentaromatics and less than 10 p.p.m. of basic nitrogen.

2. An electric cable according to claim 1 wherein said cellulosicinsulator is a paper and is wrapped around said conductive metal.

3. An oil-filled electrical cable according to claim 2 wherein saidpaper is a pure wood pulp Kraft paper with no sizing, coloring, orchemical additives and wherein said hydrorefined oil contains less than5 p.p.m. of basic nitrogen.

4. An oil-filled electrical cable according to claim 2 wherein saidpaper is capacitor grade Kraft paper of a relatively high density.

5. An oil-filled electrical cable according to claim 4 and wherein saidhydrorefined oil contains less than 5 p.p.m. of basic nitrogen.

6. An oil-filled electrical cable according to claim 5 and wherein saidhydrorefined oil contains less than 2 p.p.m. of basic nitrogen.

7. An oil-filled electrical cable according to claim 1 and whereinsaidcellulosic insulator is a Kraft tissue.

8. An oil-filled electrical cable according to claim 1 and wherein saidcellulosic insulator is creped or microcreped.

9. An oil-filled electrical cable according to claim 1 and wherein saidcellulosic insulator is creped or microcreped.

- 10. An oil-filled electrical cable according to claim 1 and wherein'said cellulosic insulator comprises cyanoethylated cellulose.

11. An oil-filled electrical cable according to claim 10 wherein saidcellulosic insulator comprises acetylated cellulose.

12. An oil-filled electrical cable according to claim 1 and wherein saidcellulosic insulator has been thermally upgraded by the incorporation ofa nitrogen-containing compound, said nitrogen-containing compound beingchemically bonded to the cellulose and serving to to protect the fibersagainst degradation.

2. An electric cable according to claim 1 wherein said cellulosicinsulator is a paper and is wrapped around said conductive metal.
 3. Anoil-filled electrical cable according to claim 2 wherein said paper is apure wood pulp Kraft paper with no sizing, coloring, or chemicaladditives and wherein said hydrorefined oil contains less than 5 p.p.m.of basic nitrogen.
 4. An oil-filled electrical cable according to claim2 wherein said paper is capacitor grade Kraft paper of a relatively highdensity.
 5. An oil-filled electrical cable according to claim 4 andwherein said hydrorefined oil contains less than 5 p.p.m. of basicnitrogen.
 6. An oil-filled electrical cable according to claim 5 andwherein said hydrorefined oil contains less than 2 p.p.m. of basicnitrogen.
 7. An oil-filled electrical cable according to claim 1 andwherein said cellulosic insulator is a Kraft tissue.
 8. An oil-filledelectrical cable according to claim 1 and wherein said cellulosicinsulator is creped or microcreped.
 9. An oil-filled electrical cableaccording to claim 1 and wherein said cellulosic insulator is creped ormicrocreped.
 10. An oil-filled electrical cable according to claim 1 andwherein said cellulosic insulator comprises cyanoethylated cellulose.11. An oil-filled electrical cable according to claim 10 wherein saidcellulosic insulator comprises acetylated cellulose.
 12. An oil-filledelectrical cable according to claim 1 and wherein said cellulosicinsulator has been thermally upgraded by the incorporation of anitrogen-containing compound, said nitrogen-containing compound beingchemically bonded to the cellulose and serving to to protect the fibersagainst degradation.